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Biomedical subjects

C J Goodacre

Publications and source records attributed to C J Goodacre.

At least 19 recordsLinked to original sources
PubMed1995

Effect of two opaquing techniques and two metal surface conditions on metal-ceramic bond strength.

The optimal conditions for opaquing techniques during porcelain application have not been confirmed. In this study the metal-ceramic bond strength was measured among one porcelain and three dental alloys, namely a gold-platinum-palladium alloy, a silver-free gold-palladium alloy, and a base metal alloy, with two opaquing techniques (a single masking layer versus a thin overfired layer followed by a second masking layer). In addition, the opaque porcelain was fired over an oxidized and nonoxidized alloy surface for the silver-free gold-palladium alloy. No significant differences in bond strength were recorded between the two opaquing techniques with the gold-platinum-palladium and base metal alloys. There was no substantial differences between the two opaquing techniques when opaque was applied over an oxidized gold-palladium alloy surface and bond strengths were substantially greater over an oxidized surface. However, when the opaque was applied to a nonoxidized gold-palladium surface the two-layer technique created a significantly greater bond strength.

Chromium Alloys↗
PubMed1991

Microleakage and shear bond strength of resin and porcelain veneers bonded to cast alloys.

Four resin veneering materials and four methods of retaining the veneer on metal castings were compared with metal ceramic restoration. Variations in microleakage were noted between the four resin materials retained by mechanical retention beads. When mechanical and chemical modes of a resin and porcelain veneer retention were compared, there was no microleakage with one mechanically and two chemically retained resin groups including one metal ceramic group. The resin materials tested understandably produced substantially lower shear bond strengths than the metal ceramic specimens. Higher shear bond strengths were recorded for the retentive beads than for the resins retained by three chemical bonding techniques. There was no direct correlation between microleakage and shear bond strength.

Acrylic Resins↗
PubMed1990

Predoctoral fixed prosthodontics education.

All current prosthodontic services will be needed well into the 21st century because millions of people are still without complete dentitions. However, knowledge of current and projected dental health needs indicates that the extent of usage of certain prosthodontic procedures will change because the number of edentulous patients will decrease. Presently there is considerable need and demand for extensive prosthodontic services and the need has been projected to grow. The demand for fixed prosthodontic services will likely increase in the future, particularly with the increased usage of new materials and treatment modalities. Recent data obtained from the American Dental Association Commission on Dental Accreditation indicate that failure rates on Part II of the National Board Dental Examinations and the prosthodontics section of Part II have remained relatively constant from 1980 to 1987. Total Part II failure rates for this time period have only ranged from 8.31 to 9.91 and on the prosthodontics section from 2.10 to 2.74. While these data do not predictably reflect clinical and technical skills or a knowledge of the most current didactic information, they do indicate that adequate knowledge had been provided to predoctoral students regarding the fundamental principles of prosthodontics. However, reductions have been made in prosthodontic curricular time. With the current escalation of knowledge in prosthodontics and allied areas and the increasing time constraints, it is becoming increasingly difficult to teach a thorough understanding of the basics and exposure to new developments. Any further reductions in curricular time will significantly compromise educational quality.

Curriculum↗
PubMed1990

Gingival esthetics.

Achieving the most desirable gingival appearance enhances the esthetic result achieved with fixed prosthodontic restorations and is most often realized when gingival health is optimized before treatment and gingival trauma is minimized during treatment. Methods of optimizing gingival appearance by avoiding soft tissue contact are discussed as are factors considered important to maintaining good gingival appearance when subgingival margins are necessary.

Dental Cavity Preparation↗
PubMed1989

Palladium-silver alloys: a review of the literature.

Since their introduction in 1973, the use of palladium-silver alloys has increased significantly and they now comprise a substantial part of the noble metal ceramic alloy sales in North America. Literature regarding various properties of this alloy system is presented with particular emphasis on castability, fit, and porcelain discoloration.

Dental Alloys↗
PubMed1989

A comparison of the physical properties of four prosthetic veneering materials.

Four resin materials used to veneer metal castings were compared by evaluating certain physical properties. Three of the materials were microfilled resins and one was an unfilled resin. Although no material proved to be superior in all of the tests, the microfilled materials were generally better than the unfilled materials. The heat- and pressure- polymerized microfilled material was inferior to the two light-polymerized microfilled materials in three of the physical property tests, superior to them in one test, and proved to be equivalent to them in two tests.

Acrylic Resins↗
PubMed1989

Principles governing the prosthodontic treatment of patients with cardiac transplants.

As the survival rate of patients with cardiac transplants improves, it is more likely that dentists will have to provide extensive dental care and it is important to know the special precautions that must be taken when treating these patients. In this report on the prosthodontic treatment of a patient with a cardiac transplant and an unstable medical history, specific dental management guidelines are proposed. The treatment illustrates an alternative to complex and prolonged restorative treatment for patients with compromised post-transplant recovery.

Anti-Bacterial Agents↗
PubMed1986

The contribution of a pinhole to the retention and resistance form of veneer crowns.

This research quantitatively compared the retention and resistance of various designs of maxillary premolar partial veneer crown preparations. Crowns were evaluated with and without proximal boxes and occlusal pins. In the absence of boxes or grooves, pins markedly enhanced both retention and resistance. In the presence of proximal boxes, pins contributed only to retention and had no significant effect on resistance. If pins are used, the cement should be spiralled into the pin hole. As resistance is usually the more crucial parameter in preparation designs, it seems that wherever efficient axial modifications can be incorporated, the pinhole modification may be of little advantage.

Cementation↗
PubMed1984

A comparison of the strength of base metal and gold solder joints.

The purpose of this study was to evaluate the procedures involved in forming high- and low-fusing solder joints between two different base metal alloys and to compare the strength of these joints with the strength of those formed between specimens made from a high-gold content alloy. The conclusions of this investigation can be summarized as follows. All but 11 of the 120 specimens failed through the solder joint, which confirms that the solder joint is usually the weakest part of a fixed partial denture. The high-fusing joints formed between the base metal alloys showed higher relative bending strength values than the high-fusing joints formed between the gold alloy specimens. The low-fusing joints formed between the base metal alloys showed higher relative bending strength values than the low-fusing joints formed between the gold alloy specimens, and the low-fusing base metal joints exhibited the highest strength values in this study. The low-fusing joints formed between gold alloy specimens consistently bent before fracturing. Solder joints fail both adhesively (separation of the solder from the parent metal) and cohesively (fracture through the solder, parent metal, or a combination of both). A correctly formed joint between gold components should show cohesive fracture, whereas adhesive fractures are apparently acceptable with base metal alloys since the low-fusing base metal joints failed in this manner but still exhibited high strength values. Voids of different sizes and locations were observed in most of the solder joints, and within each group tested there was usually less strength exhibited by the joints with larger areas of porosity.

Dental Alloys↗
PubMed1982

A comparative study of the strength of aluminous porcelain jacket crowns constructed with the conventional and twin foil technique.

The purpose of this study was to evaluate and compare the strength of aluminous porcelain jacket crowns made in the following manners: (1) the conventional technique, (2) the conventional technique with a pure alumina insert, (3) the twin foil technique, and (4) the twin foil technique with a pure alumina insert. The conclusions of this investigation can be summarized as follows: 1. Porosity was observed in all the restorations made by each of the techniques. 2. The porosity was greater at the porcelain-platinum foil interface than anywhere else throughout the restoration with both the conventional and twin foil techniques. 3. The porosity seemed to be evenly distributed along the interface, with no concentration in any area. 4. Regardless of the technique, crowns that were more porous fractured at lower values. 5. Crowns built by the twin foil technique were significantly more porous at the interface of the tin-plated platinum and the porcelain core than those built by the conventional technique. 6. Crowns constructed with the conventional technique were significantly stronger than those constructed with the twin foil technique. 7. There was no bond between the core porcelain and the platinum foil matrix in crowns constructed by the conventional technique. 8. There seemed to be a strong bond between the core porcelain and the tin-plated platinum matrix in crowns built by the twin foil technique. 9. The presence or absence of the alumina insert on crowns constructed with the conventional and twin foil technique did not affect the strength of the crowns when tested at the incisal edge.

Aluminum↗